The present invention relates to a keyless chuck for gripping an article such as a tool or the like.
A conventionally known drill chuck will be described with reference to FIGS. 1 and 2 of the accompanying drawings. The drill chuck comprises a body 1 which is formed therein with three inclined bores 2. The inclined bores 2 are arranged circumferentially about an axis of the body 1. A plurality of jaws 3 are fitted respectively in the bores 2 for sliding movement therealong. A cover 4 is rotatably mounted about the body 1. Gear teeth 6 are integrally formed at a forward end of the cover 4. An annular member 7 is force-fitted in the cover 4 and is provided with female threads 8 which is in engagement with male threads 9 formed respectively on the jaws 3. A chuck key 11 separate from the body 1 has a bevel gear 12 and a boss 13 projecting therefrom. The body 1 is formed with a bore 14 for receiving therein the boss 13 of the chuck key 11.
In use, with the jaws 3 retracted respectively into the inclined bores 2, an article such as a tool is inserted into an opening defined between forward ends of the respective jaws 3. The boss 13 of the chuck key 11 is inserted into the bore 14 in the body 1 to bring the bevel gear 12 of the chuck key 11 into engagement with the gear teeth 6 on the cover 4. The chuck key 11 is rotated to rotate the cover 4 in the clockwise direction as indicated by the arrow 15 in FIG. 1. The annular member 7 is rotated together with the cover 4 in the direction indicated by the arrow 15 so that the jaws 3 threadedly engaged with the annular member 7 is advanced respectively along the inclined bores 2 to the right-hand direction as viewed in FIG. 1. Thus, the forward ends of the respective jaws 3 move toward each other to grip therebetween the article. When it is desired to remove the article from the drill chuck, the chuck key 11 is rotated to rotate the cover 4 in the counterclockwise direction opposite to the direction indicated by the arrow 15. Rotation of the cover 4 in the counterclockwise direction causes the jaws 3 to be moved rearwardly respectively along the bores 2. Thus, the forward ends of the respective jaws 3 move away from each other to release the article from the jaws 3.
It is necessary for the conventional drill chuck described above to insert the boss 13 of the chuck key 11 into the bore 14 in the body 1 and to rotate the chuck key 11 at each time the article is gripped by the jaws 3 and is released therefrom. Thus, the conventional drill chuck is cumbersome in operation and low in operating efficiency. Further, since the chuck key 11 is separate from the body 1, the chuck key 11 might sometimes be lost or mislaid. Should the chuck key 11 be lost or mislaid, it would become impossible to perform requisite operations.